In the context of minimally invasive medicine, the endeavour is to implement an operating procedure which causes the minimum trauma for the patient. In that respect, the endeavour is to go either by way of the natural body openings of the patient as in the case of interventional endoscopy or through small incisions to directly reach the point of engagement into the depths of the tissue in order to remove tissue for diagnostic purposes, for example for histological tissue determination, or for therapy procedures, or for removal of a tumour.
The development of corresponding instruments for minimally invasive surgery made rapid progress in recent years as this operational technique affords considerable advantages for cosmetic reasons, for minimising post-operative complications and for accelerating the healing process.
Apparatuses are known by the ‘name fine needle aspiration’ (FNA) or ‘true cut needle biopsy’, having a fine needle which is introduced into a suspicious area of tissue and by means of which one or more samples of tissue can be taken purely mechanically by way of a stamping mechanism in order to subject that tissue to histological examination.
Thereafter suitable surgical measures can possibly be initiated in the event of malignant findings. The volumes of tissue which can be removed with these known needle probes are however only very small and are therefore suitable exclusively for diagnostic purposes. By virtue of the small volume of tissue which can be taken in one insertion, a plurality of insertions into the suspicious area of tissue are accordingly often required, which under some circumstances can result in malignant tumour cells being spread thereby. In addition, the levels of accuracy of the histological tissue findings are not optimum because of the small volume of tissue sampled.
U.S. Pat. No. 5,775,333 or U.S. Pat. No. 5,782,795 disclose surgical Instruments which permit relatively large volumes of tissue to be removed by multiple tissue removal from the same target area. Those known instruments involve using a vacuum-aided mechanical stamping-cutting device which reduces the number of insertions required and which in addition—because of the larger volume of tissue removed—also improves the accuracy of the diagnostic results. Those known instruments can also often be used to remove in toto relatively small tissue changes, which under some circumstances makes a subsequent Operation unnecessary.
When using the Instrument disclosed in U.S. Pat. No. 5,775,333, a needle-shaped hollow probe is introduced into the target area, for example a breast tumour. Disposed laterally at the end of that probe is an elongate opening into which the tissue to be removed is sucked. Disposed within the device is a rotating hollow blade which, by way of a mechanical forward movement, cuts off the tissue which has been sucked into the opening, within the device, and sucks it by a vacuum through the hollow probe. By successively turning the shaft through 360°, a given volume of tissue which has been previously sucked into the hollow probe and cut off therein is thus removed around the distal end of the probe, which however is often not entirely sufficient for complete removal of the medically suspicious area of tissue.
U.S. Pat. No. 5,817,034 discloses a surgical Instrument in which a hollow cylindrical blade of a diameter of up to 25 mm is driven forward to the target area. By way of a loop which is disposed at the end and which is supplied with HF-voltage, the head portion of the cylinder which is thus stamped out within the device is severed and then the entire severed cylinder of tissue is removed by way of the device. With that known System, the suspicious area of tissue can admittedly be removed in toto, but a very large amount of healthy tissue is also removed, until the probe tip has reached the suspicious area of tissue, and a relatively large scar is left, due to the large diameter of the device.
U.S. Pat. No. 5,810,806 discloses a surgical probe in which the tissue is not cut by means of a mechanical ring-shaped blade but by means of an axially non-displaceable loop which is fixed to the distal end of the hollow body and which is supplied with an HF-voltage and thereby acts as a cutting blade. In a cutting procedure, the cylinder of tissue which is severed at the periphery by the HF-loop is displaced frontally into the frontally open hollow body and then at the end of the procedure it is cut off by a windshield-like rotary movement of the loop which is supplied with HF-voltage. In the case of this known device also the tissue is completely severed only when it is in the hollow body, whereby a great deal of healthy tissue is also removed up to the time that the tip of the probe has been advanced to the suspicious area of tissue. A further disadvantage is that only the cylinder of tissue in front of the front opening of the hollow body can be removed.
DE 197 06 751 or DE 195 28 440 disclose an electrosurgical implement of the kind set forth in the opening part of this specification, in which a loop-shaped cutting element for electrosurgically cutting out tissue is oriented in parallel relationship with the longitudinal axis of an elongate hollow body and, while maintaining that orientation, can be extended in a loop-shaped configuration from the hollow body so that then the adjoining tissue can be cut out in a toric configuration by virtue of rotary movement of the hollow probe. The tissue which has been cut out can then be passed into the hollow passage of the hollow body through the same opening through which the cutting element issues, and can then be transported along the hollow passage to the proximal end of the implement. That known implement enjoys the advantage that the point of insertion is of small dimensions and that it is then possible to remove at the point of treatment a portion of tissue which externally surrounds the hollow probe in adjoining relationship. A disadvantage in this case however is that the volume of tissue which can be cut out is relatively small and is therefore not sufficient for thoroughly examining even relatively large areas of tissue.
WO 99/44506 which is published after the relevant date discloses a loop-shaped cutting element which can be extended from the hollow body in a plane which extends transversely with respect to the longitudinal axis of the hollow body, wherein after extension of the cutting element the cutting element is displaceable along the hollow body.